[swift-users] Type inference of array element type

Mark Lacey mark.lacey at apple.com
Fri Mar 24 12:51:52 CDT 2017

> On Mar 24, 2017, at 3:08 AM, Toni Suter via swift-users <swift-users at swift.org> wrote:
> Hi,
> If I declare a variable and initialize it with an array literal whose elements are integer literals and nil literals,
> the compiler will infer the type Array<Optional<Int>> for that variable:
> let arr = [1, nil, 3]
> print(type(of: arr)) 	// Array<Optional<Int>>
> However, that only works with nominal types such as Int and String. If I do the same thing with an array of tuples,
> I get a compile error:
> let arr = [(1, false), nil, (3, true)]		// error: type of expression is ambiguous without more context
> print(type(of: arr))
> Why can't the compiler infer the type Array<Optional<(Int, Bool)>> in this example? Is there a reason for this or is it a bug?

Offhand it seems like we should be able to properly handle this. Can you open a bug report at bugs.swift.org <http://bugs.swift.org/>?


> Thanks and best regards,
> Toni
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org
> https://lists.swift.org/mailman/listinfo/swift-users

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